From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755874Ab1E3HoM (ORCPT ); Mon, 30 May 2011 03:44:12 -0400 Received: from out3.smtp.messagingengine.com ([66.111.4.27]:54859 "EHLO out3.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755066Ab1E3HoK (ORCPT ); Mon, 30 May 2011 03:44:10 -0400 X-Sasl-enc: N8RdFkuZhxltSNz0X4gjaz5sdUzlPAdE1KEO7YSfDWlh 1306741449 Date: Mon, 30 May 2011 15:45:08 +0800 From: Greg KH To: Xiangliang Yu Cc: "James.Bottomley@suse.de" , "jslaby@suse.cz" , "linux-scsi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Jacky Feng Subject: Re: [PATCH 3/9] [SCSI] mvsas: Add driver version and interrupt coalescing to device attributes in sysfs Message-ID: <20110530074508.GB7806@kroah.com> References: <1306247507-6136-1-git-send-email-yxlraid@gmail.com> <20110526021809.GA22496@kroah.com> <20110526141430.GD4164@kroah.com> <20110527073302.GA16178@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 30, 2011 at 12:26:48AM -0700, Xiangliang Yu wrote: > >> +What: /sys/devices/pci///host/scsi_host/host/interrupt_coalescing > >> +Date: May 2011 > >> +Kernel Version: 2.6.39 > > >2.6.39 was released already, is this file in that release? > Yes. How, doesn't your patch below implement that option? How can it already be in the .39 kernel? > >> +Contact: yuxiangl@marvell.com > >> +Description: Determines the maximum time the 88SE94XX waits after the occurrence of a > >> + Command Done before generating an interrupt.The maximum number of the > >> + variable is less than 0x10000. > > >Why would a user, or anyone else, ever want to be able to change this? > Because different platform can get better performance by setting different value Then you need to document _how_ to do this tuning, and why someone would want to, and lots of other stuff. Don't just blindly let userspace change a value that they know nothing about. > >Why wouldn't this just be something that the driver handles > >automagically so the user never has to worry about it at all? > As for now, driver can't do it. The value need to be test, and get the best. Why don't you test it and set it to the proper value now? What would change in a user's system that require this to be changed? Size of the machine? Number of disks? Something else? It really should be automatic, people do not ever want to have to manually tune their machines anymore they should be smart enough to determine the load on them and make the changes without any user needing to do it for them. thanks, greg k-h